Abstract: ［Abstract］Objectives To understand the social support levels among breast cancer patients in Yunnan， as well as to explore the factors associated with social support. Methods　According to the unified inclusion and exclusion criteria，121 breast cancer in-patients with chemotherapy were interviewed with structured questionnaire. Social demographic characteristics， Xiao's Social Support Rating Scale，General Self-Efficacy Scale，clinical and experimental data were collected. SPSS version19.0 was used to analyze the frequency and the correlation between social support and influential variables were analyzed by using the chi-square test and non-parametric test. Results The levels of social support in total， objective social support， subjective social support and utilization degree for breast cancer patients were（49.43±5.69），（13.35±2.51），（27.59±3.78），（8.50±1.98）respectively. Marriage status and self-efficacy were associated with social support level significantly. The influencing factors such as age， education level， marital status， occupation， income， place of residence， religion， medical expenses payment type， self-efficacy were included in the univariate analysis. However， only marital status and self efficacy were positively correlated with social support（p<0.05）. Conclusions The breast cancer patients in Yunnan have a higher social support level overall. Having-marriage status and higher self-efficacy have a positive influence on breast cancer in patients' social support level.